Pressure-operated switch



March 5, 1929. F J, HElDEMA'N 1,704,191

PRES SURE OPERATED SWITCH Filed Sept. 2l., 1925 l l y Ill i 'O wlmllf mi ffy/ @mauro/6 Patented Mar. 5, 1929.

UNITED STATES PATENT OFFICE.

FRED J. HEIDCEMAN, OF DETROIT, MICHIGAN, ASSIGNOR OF NINETY PER-CENT T0 THOMAS C. WHITEHEAD, OIF RIVER ROUGE, MICHIGAN.

PRESSURE-OPERATED SWITCH.

Application led September 21, 1925. Serial No. 57,792.

This invention relates to pressure operated-switches and more especially to devices of this character particularly adapted for use in connection with refrigerating apparatus. y A .l

The invention has among its objects to simplify, render more efficient, and improve generally devices of this general character, and these, as well as other objects, advantages, and novel details of construction will be made l-Inore apparent as this description proceeds, especially when considered in connection with the accompanying drawings `wherein one illustrative embodiment of this invention is illustrated and wherein Figure 1 is a vertical sectional view taken through a pressure operated switch constructed in accordance with this invention.

Fig. 2 is a horizontal sectional view taken substantially on the. plane indicated by line;

2 2 in Fig. 1. l

Fig. 3. is a vertical sectional view taken substantially on-the plane indicated by line 3*-3 in Fig. 1; and

Fig. 4 is a sectional elevation showing a pressure operated switch in another of its operative positions.

Referring now more particularly to the drawings wherein like reference characters indicate like parts, it will be noted that the structure consists essentially of a base 10 which may in practice be one of the structural elements of the refrigerating apparatus, to which there is attached an externally threaded stud plate 11 secured to the base 10 as, for instance, by means of a bolt 12.

A housing or casing 13 rests preferably upon base 10 and threadedly engages stud plate 11 and forms a container for the collapsible tluid pressure device 14C known to the trade as a sylphon. In addition to the flexible portion, the sylphon comprises a lower head 15 formed with a tubular extension 16 extending out through casing 13 and by means of which attachment is made to, for instance, a closed conduit containing a medium res onsive to the temperature inv the brine ta of the refrigerating apparatus.

The head member 15 rests on stud plate 11 and by passing tubular extension 16 through the housing 13 head 15 is rigidly assembled with relation to the remaining structure j The reference character 17 indicates the movable head of the sylphon which has conf nected thereto a plunger or post 18.- The movable head 17 is preferably centrally depressed and the plunger 18 is connected thereto at the bottom of this depression. By such a construction a greater eompactness is obtained.

Post 18 is preferably headed as shown at 19, this head being engaged by a collar '20 which in turn is secured to sylphon head 17. The upper end of post or plunger 18 is internally threaded for engagement with an externally threaded post extension 21 which is provided with a ca'm head 22 formed with a pair of meeting oppositely extending sur- .faces 23 and 24;. Surface 24 constitutes a cam face while surface 23 which extends at an acute angle thereto constitutes a shoulder. By forming the plunger 18 of two sections threadedly united, the operative length oi the plunger may be varied, thus affording an adjustability eEecting the eilieiency of the thermostat 1n a manner to be made more apparent later.

Casingv 13 is formed with a threaded aperture centrally of its upper wall for the reception of an externally threaded cap nut or plug 25, this latter member being centrally apertured to permit the passage therethrough of plunger 18. Plug nut 25 is shouldered at its under side to provide aseat for spring 26 which bears thereagainst and against movable head 17 of the sylphon. The tension of spring 26 may be adjusted by means of plug nut 25 and by means of this adjustment the operation rof the sylphon may be controlled lso that the thermostat will operate at the desired pressures dependent upon the temperatures in the brine tank.

Projecting upwardly from casing 13 is a pair of uprights 27, and pivotally connected thereto, as at 28, for oscillatory Inovement is a switch control arm 29. vUprights 27 are provided with a stop 27 for limiting the oscillatory movement of arm 29. Arm 29 is formed with a vertically lextending opening to permit the free passage therethrough of the upper end of the plunger 18. The end of arm 29 opposite to its point of pivotal support is of a tubular constructionv to receive plunger 30, this plunger being Aformed at the end adjacent cam head 22 with 30 is normally urged towards cam head 22 by means of a spring 32 which abuts on the one hand against a shoulder formed on its plunger and on thel other against set screw 33 threadedly engaging the interiorly threaded end of arm 29. Screw 33 is also employed to secure to the end of arm 29 a carrier 34 for a roller 35. This roller is adapted to makevcontact between a pair of spring contact arms 36 by being forced therebetween, when arm 29 is in the position shown in Fig. 1, in a manner more clearly apparent in Fig. 3. Contact arms 36 are carried by a block of insulating material 37 mounted on the side of housing 13. Electric conductors, which form Ya,partfef the circuit including the electric motor for operating the compressor, are connected to binding posts 38. The construction involving the roller and spring contact arms 36 insures a-satisfactory electrical contact at all times inasmuch as the point of contact between the roller and arms 36 will be constantly changed due to the rotation of roller 35, thus eliminating the possibility of the pitting of contact points. A stopl 27 limits the movement of arm 29 in its downward direction.

manner shown clearly in Fig. 1, encloses all of the thermostat structure previously described'for protecting the same.

In operation, the circuit to the compressor Amotor is closed when switch operating arm 29 is in a position shown in Figs. l and'3. In this position, the head 31 of plunger 30 is under shoulder 23 of plunger 18, and with the sylphon in the position shown in Fig. l, contact roller 35 will be held between contact'ar'ms 36, and a circuit thus maintained. As the temperature in the brine tank falls, the pressure in sylphon 14 will correspondingly decrease until it reaches a point wherein spring 26 will overcome-the pressure in the sylphon and consequently move plunger 18 downwardly. Owing to the rounded portions of shoulder 23 and head 31, plunger 30 will be moved axially against the tension of spring 32 so that plunger 30 will become diS- lodged from beneath shoulder 23 permitting head 31 to ride on cam surface 24 and thus permit arm 29 to oscillate about its pivot 28 in a position substantially as illustrated in Fig. 4. Roller 35 willconsequently be moved out of contact with arms 36 and the circuit to the compressor motor will be broken. Arm 29 will be held in this raised position by the inuence of spring 32 on plunger 3@ which tends to cause head 3.1 to ride upwardly. on cam surface 24.

Then the temperature of vthe brine tank begins to rise, the pressure in s iphsn wili be correspondingly increased andywhen such a pressure is attained suiiicient to overcome the tensien of spring 26 plunger 18 will be movedv upwardly. 'During the upward movement of plunger 18, cam surface 24 will be moved vertically with reference to head 31 of plunger 30 until head 31 snaps under shoulder 23. This movement of plunger 30 causes the downward oscillation of arm 29 to again bring roller 35 in engagement with contact arms 36 whereupon the circuit to the compressor motor is again completed. Spring 32 will'lmaintain the parts in this position until the pressure in sylphon 14 has again fallen below the tension of spring 26 whereupon the cycle of operations just described will be repeated.

From the foregoing it 'will be apparent that a snap switch action is obtained irrespective of the degree of rapidity of the rise and fall of the temperature ofthe brine tank.

Consequently danger of arcing at the contact points and the accompanying ,hazards are eliminated. Furthermore the arrangement is such that the contact roller 35 will be positively maintained in its operative or inoperative position 'at all times except at it is shifted by the operation of the sylphon.

The construction just described may be .Y cheaply and durably. manufactured, as- An outer` housing member 36 may be provided, which when secured in position in the sembled and repaired with facility and easily adjusted in dependence upon the requirements of the refrigerating apparatus with which it is installed.

While one embodiment of the invention has been described and illustrated in detail it will be immediately apparent that various changes and modifications may be resorted to' without departing from the ,spirit and scope of this invention, and to this end reservation is made to make such changes as may come within the purview of the accompanying claims.

I claim:

1. In a pressure operated circuit maker, a fluid pressure device comprising a casing, a switchl associated with said casing, a cam member actuated by said device, contact arms carried by said casing at one side of the cammember, a switch arm having one end pivoted upon said casing at the other side ot' said cam member and having a roller at the opposite end thereof adapted to engage the Contact' arms aforesaid, and a spring infiuenced plunger carried by said arm and engaging said cam member for oscillating said arm. y

2. In a pressure operated circuit maker, a fluid pressure device comprising a casing, a switch associated with said casing, a cam member actuated by said device, a member extending upwardly from said casing provided with means engageable with the cara member 16er guiding the same and a switch arm for actuating said switch pivotally connected to the member aforesaid.

3. 'In a pressure operated circuit maker, a duid pressure device comprising casing, a

switch associated with said casing, a cam meinber actuated by said' device, a member extending upwardly from said casingv provided with means for guiding said cam member, and a switch arm for actuating said switch pivotally connected to the member aforesaid having a vertically7 extending opening therein to permit the free passage of the cam member therethrough.

4. In a pressure operated circuit maker, a fluid pressure device comprising a casing, a switch associated with said casing, a projection upon said casing, an arm for actuating said switch pivotally mounted upon said projection, and anti-friction means mounted upon the pivotal connection aforesaid and engageable with said cani to guide the same.

5. In a pressure operated circuit maker, aswitch, a iiuid pressure device, an oscillatory arm for actuating said switch, a cam member adjustablyinounted upon said uid pressure device and operated thereby, e spring influenced plunger arranged Within said arm and engaging said cam member for oscillating said arm, and anti-friction means arranged within said arm and engageable with the opposite face of said cem member for guiding the latter.

In testimony whereof I aiiix my si gnature.,

FRED J. HElDEi/IAN. 

